L950 shuts down by itself or blacks out the screen

I've seen three or four times where my L950 appears to be shut down. As in the screen is off and pushing the power button does seem to do anything. Eventually I hold down the power button for a while (more than 4 seconds, maybe 10 seconds) and the phone eventually plays a tone and reboots(?) itself.

Any one else seeing their L950 seemingly shutdown by itself? What is causing it and how do I fix it, if I can?

I've seen three or four times where my L950 appears to be shut down. As in the screen is off and pushing the power button does seem to do anything. Eventually I hold down the power button for a while (more than 4 seconds, maybe 10 seconds) and the phone eventually plays a tone and reboots(?) itself.

Any one else seeing their L950 seemingly shutdown by itself? What is causing it and how do I fix it, if I can?

Experienced exactly that a couple of days ago!
The phone went all black and didn't respond at all. Ended up pulling the battery, forgot about soft reset.
After that it has been fine.

I am a part of the Windows Insider program so I should have the latest builds but something absolutely needs fixed as I've run into this issue about 3 times in the past week. My previous 920 never glitched like this.

I have seen this problem WITH reboot once or twice. Without reboot few more times. Usually the screen just stays black and I can see the red light from iris-scanner and if I look at it I can hear the unlocking sound but the screen stays black/off. When I lock the phone again then glance screen comes on and I can press the power button and screen lights up normally.